A dual-loop optoelectronic oscillator (OEO) with reciprocating optical path is presented. The utilization ratio of delay for a fiber can be doubled due to feedback modulation after the optical signal passed through the Mach-Zehnder modulator (MZM) twice. And two optical loops with different lengths can be formed in the same way. This mechanism is based on the theoretical analysis of the oscillate condition and mode selection principle of the dual-loop configuration about this dual-loop configuration is analyzed. Furthermore, compared with the conventional optoelectronic oscillator, the experimental results show that such dual-loop configuration can effectively improve the side-mode suppression ratio and the side-mode suppression ratio is 48.33 dB, the single side band phase noise is -97.35 dBc/Hz at 10 kHz of frequency offset. In addition, the consumption of fibers can be reduced and the control parameters are sampled since no extra active devices in this dual-loop OEO are needed. The random interference and beat noise can be eliminated when the signal in the two loops transmits in opposite direction.